Process of preparing alkyd resins



atented 19,, new

- PROCESS @F PREPING ALK RESINS Edward C. Haines, Moorestown, N. 3., assignor to Geo. ll). Wetherill Varnish 60.,

Inc, Camden,

N. 3., a. corporation of Pennsylvania Application June 6, 1944, Serial No. 538,937

This is a continuation-in-part of Edward C. Haines' application, Serial No. 447,809, filed June 20, 1942.

The invention relates to the production of alkyd resins and is more particularly concerned with a process for preparing oil-modified resins in a novel, cheaper, and more expeditious manner.

In the past, it has been found generally difficult to incorporate, under atmosphere pressures, an oil-modifying ingredient into an unmodified alkyd resin to form a homogeneous product unless resort is had to indirect methods or to the formation of intermediate compounds. in other words, in order to disperse the resin formed by the reaction between a polyhydroxy alcohol and a polycarboxylic acid in the oil-moditying agent, it has been generally necessary first to form an intermediate compound by combining part or all of the oil with either part or all of the polyhydroxy alcohol. In some cases, intermediate compounds have been formed by comblning part or all of the oil with part or all of the polycarboxylic acid or its anhydride, while in other cases intermediate compounds have been formed containing an excess of one of the ingredients. In the case of glyceryl-phthalate resins, it has been the general practice to replace part or all of the oil with an equivalent mixture of fatty acid and glycerine.

One of the objects of the present invention is to combine the resin-forming component directly with an oil which is normally difiicult to combine without employing indirect methods or preparing an intermediate compound.

This is accomplished in accordance with the present invention by providing a continuous method for preparing oil-modified alkyd resins. Essentially, and briefly stated, it has been found that the oil-modifying component may be directly and smoothly combined with the resiniorming component if a uniform mixture of a polyhydroxy alcohol and a polycarboxylic acid (or anhydride) in liquid form, with or without other resinous bodies, as one ingredient; and a fatty oil or oleoresin as a second ingredient, are continuously added in aliquot amounts to a partiall resinified reaction mixture of these two ingredients at a suitable combining temperature. Such a continuous process results in a clear, physically homogeneous, partially combined resin which may be used as such. For example, the product of the initial reaction is useful as a modifying ingredient in varnish. On the other hand, as more articularly pointed out hereinafter, this initial reaction mixture may be further processed, as by cooking, either by batch, or in a continuous manner to produce a homogeneous resin of low acid number.

The production of physically homogeneous resins in accordance with the present invention and the distinct advantages resulting from the present process, may be explained, in connection with oil-modified glyceryl phthalate resins as follows:

The chemical combination of glycerine and phthalate anhydride involves an esterification reaction in which water is evolved. This reaction is reversible and the liberation of water, if retained in the mass, will produce an equilibrium at partial esterification, depending upon the concentration of reactants. In a batch process the water of esterification is continu= ously driven ofi, is not replaced, and the reaction mass gels or polymerizes as it approaches com plete esterification. This may also be true of partially oil-modified alkyds, depending upon the degree of modification.

It is a salient feature of the present invention to maintain equilibrium in the reaction mixture to prevent gel formation. This is accomplished by allowing the reactants to comingle in a continuous manner to cause a continuous evolution in situ of water of esterification. Such a continuous process assures the presence of water at all times in the reaction mixture, regardless of the fact that the reaction temperature is above the boiling point of water, that is, as fast as water is driven off, it is continuously and immediately replaced in amounts sumcient to maintain eo1ui= librium. This inhibits or prevents gel formattion or polymerization, thus enabling the oil to react with the partially esterified and/or modified alkyds.

\ As pointed out hereinafter the amount of water of esterification may be augmented by the continuous addition to the reaction mass-of water from an extraneous source. For instance, water may be continuously introduced by first diluting the resin-forming ingredients with water and all then continuously adding the thus'diluted ingredients to the reaction mass. Also, water may be added by directing a continuous stream of steam through the reaction mass.

In connection with the attainment of equilibrium in oil-glyceryl phthalate mixtures, the following observations should be made:

Oil is soluble in an oil-modified alkyd in an amount depending on the extent of modification. Also oil combines slowly with an oil-modi- 2 .1- fled alkyd at esteriflcation -temperatureslj- A partially esterifled oil-modified alkyd, "containing 1 many uncombined hydroxyl and carboxyl groups,

will combine relatively quickly with more phthalic anhydride and glycerine or with a partially esterifled compound of the two. At esteriiication temperatures water will be evolved during such addition. When the addition is made continuous, in accordance with the invention, this water of esteriiication establishes an equilibrium in the reaction mixture, because the reaction is reversible.

Oil can also be added to this mass if the rate of oil addition is not so great as to cause immiscibility with the partially esterifled alkyd, due to high uncombined oil concentration, before it has had time to combine. 7

Assuming, in the present process, that the reaction has begun, and-that the reaction vessel contains a homogeneous-equilibrium mixture, oil

is added to it slowly at the rate it is combining with the mixture. The rate of combination is determined by the temperature and by the concentration of uncombined oil in the mixtiire. Phthalic anhydride and glycerine or a partially esterified mixture of a compound of the two are added at such dude that. the formula remains constant. They combine with the free hydroxyl and carboxyl groups'present to form oil modified alkyds of higher alkyd content than the average alkyd content of the reactive mass and at the same time water is liberated which, as pointed Pounds Linseed oil (raw) 480 Phthalic anhydride. 360 Glycerlne. 160

The linseed oil is stored in vessel I, which is calibrated in a suitable manner so that reference might be had at all times as to the amount of oil in the container and/or the rate of passage therefrom to reaction vessel 3, referred'to more particularly hereinafter. The resin-forming components are stored in vessel 2, likewise appropriately calibrated.

In accordance with this specific example, the resin-forming component was prepared as follows: The glycerine and phthalic anhydride were combined by cooking at elevated temperatures to form the half-ester. The temperatures and time of thiscooking'operation may vary over a fairly wide range. In the present instance 160 lbs. .glycerine and 360 lbs. phthalic anhydride were melted together at 260 F.- The reaction was allowed to proceed without heat until a sample was clear when cold. The temperature was then raised to 350 F. and held fifteen minutes. The final product seems to be improved by longer cooking at; 350 F. but the resin-forming component is not so easily handled due to its viscosity.

when cold this half-ester is a clear viscous material. In order to make it flow at room temperatures, the half-ester was diluted with water in the proportion of eighty parts water to the compound formed from three hundred sixty (360) parts phthalic anhydride and one hundred sixty (160) parts glycerine. The water content may be varied considerably to produce the proper fluidity. When other acids or alcohols are used, the temperatures, to give the proper combination, may vary somewhat. It is also possible to use acids which dissolve in a mixture of water and glycerine without combining them first under heat, as in this case.

Reaction vessel 3 was initially charged with a preformed linseed oil-modified phthalic anhydride glycerine resin. This preformed equilibrium mixture was prepared by adding oil and resin component manually to a small amount of modified alkyd prepared by the batch process until a sufficient quantity was obtained.

This preformed charge is heated in reaction vessel 3 by any convenient heating means H and held at a temperature of about 440 F. The average rate of addition is about thirty-one (31) ounces of the total raw materials shown in the above formula during one hour to one hundred ounces-of material in reaction vessel 3. At the indicated ingredient addition rate and temperature, the mass is in the state of ebullition,

no artificial agitation is necessary, and a physically homogeneous mixture is continuously maintained. The reaction mixture formed in reaction vessel 3 may be drawn oil as formed, to be used directly as a varnish-modifying agent, as pointedout hereinbefore, or it may be drawn through the valve 4 into a second reaction vessel 5 where the reaction mixture is cooked at a temperature from 420 F. to 480 F. Heat is supplied by heating element H. As indicated above, reaction vessels 3 and 5 are equipped with thermometers or other temperature indicating media T and T. Naturally, the temperature to be maintained in reaction vessel 3 will depend upon the type of reactants employed. Generally speaking, the range of temperature will vary from 350 F. to 525 F., and preferably the mixture is held at temperatures from 375 F. to 475 F.

' Reaction vessel 5 is also preferably equipped with agitating means and in the drawing this is shown as a tube 8 through which is passed an inert gas, such as carbon dioxide or nitrogen to eifect agitation. The average cooking time in reaction vessel 5 is varied by adjusting the level of the reaction mixture therein in relation to the level of the mixture in reaction vessel 3. In this specific example, the level and volume of the material in reaction vessel 5 is about the same as the level and volume in reaction vessel 3, giving an average cooking time of approximately three hours. The final resin has an acid number of approximately 20 and may b drained oif continuously through outlet 1. It has been found that the rate of addition of the materials to reaction vessel 3 may be varied considerably.

As shown in the drawing, reaction vessels 3 and 5 are shown open to the atmosphere and uninsulated. It is understood, of course, that these vessels could be closed and covered with heat-insulating material.

while the upper limit wouldbe: determined by an impractically slow reaction. The limits will vary both with the nature of the oil component andthe nature of the resin-forming component. The rate at which combination takes place will also vary greatly not only with the ratio of the components but also with the composition of each component. Naturally, the degree of unsaturation or type of unsaturation of the oil employed will affect the rate. of the combination.

I claim:

1. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling the fatty oil with the allwd resin-forming components at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in. the mass and the water evolved being continuously replaced at the rate at which it is evolved.

2. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling the fatty oil with a freeflowing mixture of a polyhydroxy alcohol and a polycarboxylic acid at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it is evolved.

relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being con- .tinuously replaced at the rate at which it is evolved, continuously transferring the reaction mixture so formed to a second heating zone, and continuously drawing oil the oil-modified alkyd resin from said second heating zone.

'6. A process of combining fatty oil with alkyd resin-formingcomponents, which comprises continuously intermingling linseed oil with a mixture of a polyhydroxy alcohol and a polycarboxylic acid at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it is evolved.

7. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling linseed oil with a halfester of glycerine and phthalic anhydride at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such 85 that homogeneity obtains at all times in the mass 3. A process of combining fatty oil with alkyd tinuously intermingling a polyhydroxy alcohol tinuously intermingling the fatty oil with a mixresin-forming components, which comprises conture of glycerine and phthalic anhydride at a constant rate andat an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions and the water evolved being continuously re placed at the rate at which it is evolved.

8. A process of combining fatty oil with alkyd resin-forming components, which comprises conand a suspension of a polycarboxylic acid in a fatty oil at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reacof the reactants and reaction products and to evolve water continuously at a constant rate, therate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it is evolved. A

4. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling in one heating zone the fatty oil with the alkyd resin-forming components at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constantin the mass the relative proportions of the reactants and reaction prod nets and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it. is evolved, continuously transferring the reaction material so formed to a second heating zone, and continuously drawing ofi the: oil-modified alkyd resin from said second heating zone. V

5. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling in one heating zone linseed oil with a mixture of glycerine and phthalic anhydride at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the tion products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it is evolved.

9. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling a polyhydroxy alcohol and a suspension of fumaric acid in a fatty oil at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant and a suspension of maleic acid in a fatty oil at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constant in the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it is evolved.

11. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling fatty oil, glycerine and phthalic anhydride at a constant rate and at an elevated temperature at substantially atmospheric pressure so as to maintain constantin the mass the relative proportions of the reactants and reaction products and to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously replaced at the rate at which it is evolved.

12. A process of combining fatty oil with alkyd resin-forming components, which comprises continuously intermingling the fatty oil with the alkyd resin-forming components at a constant rate and at an elevated temperature so as to maintain constant in the mass the relative proportions of the reactants and reaction products and'to evolve water continuously at a constant rate, the rate of addition of components being such that homogeneity obtains at all times in the mass and the water evolved being continuously i replaced at the rate at which it is evolved.

EDWARD C. HAINES. 

